1. Field of the Invention
The present invention relates to safety means for enabling complicated operations of robots to be safely, appropriately and smoothly effected. The present invention also pertains to means for ensuring safety in the operation of industrial machines, hand tools, vehicles and so forth.
2. Description of the Related Art
Robots, such as industrial robots, are generally put into practical use in various fields. High-technology robots which possess excellent working abilities have heretofore been developed for use in painting operation, e.g., robots which are capable of automatically detecting configurational features of various objects which have irregular shapes or are arranged at random by detecting the respective configurations of the objects, thereby enabling automation of a manufacturing operation in which a plurality of types of products are produced in small quantities; robots which are capable of detecting multi-dimensional positions of objects to be painted and thereby providing high operability which enables automation of the painting operation; and intelligent robots which have tactual senses. These robots which have the above-described excellent functions, that is, the tactual function and the function of detecting a random arrangement or multi-dimensional positions of objects, still involve risks in operation. More specifically, when a working arm of such a robot in operation hits a foreign body which suddenly and accidentally enters the robot working area, or an object of painting other than those which are included in a predetermined working program, due to functional error such as sensing error or tactual function error, the impact load generated as a result of this collision may damage the function unit incorporated in the robot main body. As means for preventing occurrence of such an accident, one type of robot has heretofore been provided with a buffer device such as that shown in FIG. 14. The buffer device 40 comprises a fixed plate 42 secured to a swivel arm 41 of a robot main body (not shown), a fixed plate 42a secured to a working arm 43, and a leaf spring 44 having both ends thereof respectively secured to the fixed plates 42 and 42a.
The buffer device 40 operates as follows. When the working arm 43 hits a solid body such as a foreign body which accidentally enters a predetermined working area of the working arm 43, an object to be worked, an object other than those which are included in a working program, or a portion or member, e.g., an accessory member of the object to be worked, which is intended to be out of a predetermined area of the movement of the working arm 43, due to a failure in a predetermined sensing function or tactual function, the impact load generated at this time can be practically absorbed by virtue of the elasticity of the leaf spring, so that it is possible to buffer the impact.
However, since the robot continuously conducts the operation for a predetermined working area even after the above-described accident has occurred, the impact load often causes the robot main body to be damaged, or the leaf spring may be deformed or broken, resulting in displacement of the working arm 43. When the working arm 43 is displaced or offset, it is completely impossible for the robot to automatically restore the working arm 43 to its normal position, and it is necessary to re-teach the robot. Since a long time is required to effect the re-teaching operation, the whole operation of the robot must be stopped during this period, which disadvantageously leads to the stop of the operation of the whole manufacturing line.
Further, various means have heretofore been adopted for avoiding or absorbing the impact generated during the machining or assembling operation of an automatic loader, a lathe or other industrial machines, and the continuous vibration of a chain saw or an air hammer, and for ensuring safety at the time of collision of a motor vehicle. However, most of these means are incomplete and unsatisfactory.